The invention is directed to an electropneumatic controller having two solenoid operated pneumatic valves, each of which is respectively provided with a regulating pressure nozzle, an exhaust nozzle, a discharge leading to a power amplifier and a hinged armature that is driven by a magnet system and alternatively closes the regulating pressure nozzle or the exhaust nozzle.
The application of position controllers is described in German Utility Model No. G9110959 and German Patent Application DE-A13727008 corresponding to U.S. Pat. Nos. 4,922,952 and 4,925,498 incorporated herein by reference. Two solenoid valves are typically used for moving the final control element, such as a control valve element, from a first to a second position and to move the control element back from the second to the first position.
Such position controllers typically require auxiliary electrical energy, for example in order to be able to test the unimpeded movement of the adjustment device provided with the position controller in an early stage of assembly. This makes assembly more difficult, particularly when the assembler is not authorized to carry out the electrical connection of the device.
It is therefore desirable to fashion the initially cited, pneumatic position controller such that the position controller can be brought into any desired position, particularly into the upper and lower extreme position without auxiliary electrical energy. This is required, for example, for setting the zero point.